Door drive system



lMarch 11, 1952 F. RICHARDS DOOR DRIVE SYSTEM Filed MaIQh 2, 1949 /7 H 45 i 2f-2j,

f5' c f* 2f f Alim 55 7 I "u l lNv-'ENTOR GEORGE F. /P/cHH/Pas Il ATTORNEY Patented Mar. ll, 1952 4UltlTliljl) STATES PATENT 0F F ICE George .,F. Richards, Garden Cita AN- 31.-, `@Signor -to Teletronics Laboratory, Inc Westbury,

N. X., a :corporation of New York Application March 2, 1949,1,Serial'iNo.79,215

,3 laims. (01.268159) The present invention 4isdn the xieldof control equipment for vmovable objects, .and ideals with the provision 4of `an .arrangement particularly suited .for raising .and lowering movable `.doors such as sectional overhead .garage .doors This invention contemplates `an `arrangement for serving the udual purposes .of .maintaining a desired normal tension in a drive belt .coupling a -motor drive lpulley tolalpulley arrangedonthe -door suspension system, .and for yautomatically tightening the drive belt uponibringingithe Vdoor to the limit of its Vzone of movement, in *suche way as to preventany bounceorizbacklash of :the door andto hold rit locked rmly1initslimitposition.

An object of ithisinventionis toiprovide amechanical system of .maximum :simplicity for accomplishing the above-mentioned dual `purposes of normal belt `tensioning `and of substantially tighteningfand locking the belt upon the arrival of the door orother movableobject ata desired extreme of itsltravel, e. g., atone :orbothofthe limit positions of the sectional overheadigarage door.

This is accomplished by arrangingabelt :drive system extending between a :motordrive pulley and a driven `pulley coupled touthe movablesobject such as the garage door, with one ormore pivotally suspended idler pulleys Vurged by `a spring linto positions Vin `contact with .the drive belt.

Preferably, the pivotaLaXis for. thef-idler-pulley suspension arms `is aligned substantially .with ,the `motor drivepulley axis. The spring tension isiso arranged as to-cause-appreciable deilection ofthe aforementioned leg of the belt, e. g., to form an angle of the orderof -150Q to :130 betweenftlie portion of the belt extending `from the .idler to the motor pulley and the `portionextending to the driven pulley. This `normally keeps the 4belt under the desired tension duringupward or .downward drive of the door.

Upon driving the door or other movable object to the `predetermined limit, e. g., kthe lowermost limit position of the garage door, the torsional reaction in the driven pulley greatly increases, so that the leg of the belt which has been mov ing toward the motor pulley is greatly'ftightened, and is stretchedv to an abnormal length. Accordingly, the opposite leg ofthebeltfthatilegchare Aacterized by `movement from the motorlpulley toward the driven pulley during `descentof :the door,is caused to have somewhatincreasedlength so that the spring ,acting `on gtheidler pulley `and -dler ,pulleyl iarm .materiallyaincreases; the :,deec- 2 tion Qi ,thislegof the belt, tending to increase the `resistancetorurther movement-,of the belt. Generally .Speaking there isa slight tendency of the `door;tc; lrebo un d uponreaohing its limit of downwardmovement, `but such rebounding then tends toause the lbeltmovement direction to reverse, and with `the considerably sharpened angle of dellectionof the leg'against which the idler pulley ,am-,S andtheponsequent binding of `the belt on this ',nulley, thisibriefbelt reversal tends to move `ztheidler ,pulley toa 4stillfurther extent and further increase .the belt deflection. As :a conseouence., the beluissp greatly tightened alone with the increased deection of the idler pulleyas substantially v130 .lock the `belt against appreciable slipandjo llesststaunchly such rotation of the driven pulley Las ,normally must accompany re- `.bonndnf the-door.

'rlfheserfeatures are illustrated and clarified by reference yto fthe accompanying drawings whereiF'g. Il ,ishowsimainly `inside elevation, an ar- .,rangement of ya ,garage door drivesystem ern- Abodydlg `.the lockrdownfeature of the present in- :.-vlention Eis .2 shows,affur ther side elevation taken from thesQppQsitedirection, the `view `in Fig. 2 repre- :senting `:thesuccessive positions of the idler system lust asthedoor reachesits lowermostpostion;

Fig. 3 illustrates a preferred embodiment of the present invention, employing two .idler pulleys, onezactngpngeach belt leg; `and zlig. 4..illus tra tes1the Imannerin which the idler Pulleysoperazte in contact with the broad flat loa-ck offthe Vi-belt.

Referring inowlgtoligs. f1 and 2, asectional ga- Iagrdoolsystem il is 4illustrated as including axplurality of :hingedly connected door sections i3 lhavinggztheir hinge pivot axes guided in a pair of -parallel guidetracks, one of the tracks i5 being :visible in :the `-vewiof E'ig. ,1. Thetrack I5 and the similar trackwhch is not visible in thisgure ,include ,parallel-,vertical portions and parallel substantially horizontal or very slightlyinclmed por ;tions;with;a;cu1lve of appreciabe radius being .fprinedftherebetvveen- Ehe door sections AI3 are illustratedjin cross sec,tion,;four or more such sections usually being provided in 1a door unit.

,The upper portion Vof the iront `wall of the fbuildnggin Whichithe door system is installed is :illustrated at I Lthe ,door frame `being shown at As the total Weight of the `movablesections of overneadydoorsystems,of this type usually is a few hundred pounds, it has been the custom to provide a large counterspring system acting in the direction in opposition to gravity, i. e. to tend to lift the door, to provide for substantially balanced action of the movable door system. A desirable and popular type of counterspring system for this purpose comprises a counterspring shaft 2l extending substantially horizontally and substantially parallel to the wall Il, over a span somewhat exceeding the span between the guide 'i tracks. A winch-type pulley22 is fixed to this shaft near each end thereof, and is provided with a suspension cable 23 extending down to a point at which it is tied to the lowermost door section. IThe counterspring (not shown) is fitted over the counterspring shaft 2i and attached thereto at one end, and anchored at its opposite end. This counterspring is arranged to be deflected only slightly from its non-stressed condition when the door is fully raised, and to be increasingly deflected and stressed as the door moves downward, until at the lowermost position of the door, it exerts a force through the suspension cable 23* and the similar suspension cable at the opposite end of the counterspring shaft, this force substantially equalling or slightly exceeding the total weight of the door sections.

The parts of the sectional door and guide and counterspring system thus far described constitute Well known and generally used overhead door systems, and in the past, have usually been provided with handles and key-operated locks for full manual raising and loweringeof the overhead door.

In the present arrangement, a motor drive system including a motor 3| and control circuits accessory thereto in a box 33 are suspended by a substantially rectangular frame 35 from track I5. One vertical member 3l of this suspension system preferably is made with great breadth for enhanced rigidity of the suspension frame 35. Y

The motor 3| is provided with a V-belt drive pulley 39 internally geared to the high speed rotor for reduced pulley drive speed. This pulley 39 is coupled by a V-belt 4I to a V-belt pulley 43 rmly attached to the counterspring shaft 2l.

A switch 45 is provided for selectively turning off the motor 3I, or operating it in one direction to drive Vthe door sections I3 upward or in the opposite direction to drive them downward to close the door.

With the suspension cables such as cable 23 passing over the winch pulleys and downward in the counterclockwise direction as viewed in Fig. 1 and the clockwise direction as viewed in Fig. 2,

the upper leg of the belt is made to travel from Y pulley 43 when the door is raised. I

In accordance with the principles of the present invention, an idler pulley arrangement including a pulley 5I and a movable idler support arm 53 is arranged with a spring for appreciably deiiecting that leg of the drive belt GI which moves toward the driven pulley 43 during the descent of the door. In this case, the cable 23 being passed counterclockwise over the winch-type pulley 22 and downward as seen in Fig. 1, this idler system 5I, 53, 55 is made to act against the upper leg of the belt 4 I.

The spring 55 is adjusted through the use of i turnbuckle 5l to such tension as normally to produce an angle of the order of to 160 between the right-hand and left-hand parts of the upper leg of the belt 4 I.

Ereferably, though not necessarily, the pivotal axis of the idler pulley arm may be made coincident with the axis of the motor drive pulley 39; or if not coincident with the motor drive pulley axis, the pivotal axis of this arm should be nearer to the axis of the motor drive pulley than the region at which the idler pulley acts against the belt 4 I.

As viewed in Fig. l, the switch 45 is shown with its-control arm set for downward drive of the door and the door sections are illustrated as having descended through the greater part of the distance toward the closed door position.

Fig. 2 shows the system with the door fully lowered, the uppermost of the sections I3 being in contact at its upper front edge with the doorfacing members of the frame i9. The idler pulley arm 53 and pulley 5I are shown in full lines as deflected to the normal extent prevailing during movement of the door and thus, at the position prevailing until the door jams shut. Upon the full closure of the door, the continued torque exerted by the motor 3i' in the direction indicated by arrows 6I and 63 produces appreciable tension in the lower leg of the belt 4I, because the motor now acts against the very great torque of the fully wound counterspring unaided by the weight of the door I3. The motor, being of proper capacity for driving the counterbalanced door, is quite unable to cause further revolution of the pulley 43 and the counterspring shaft 2l against this excessive load but the lower leg oi' the belt 4I being now accordingly very tightly stretched, the upper leg of the belt is appreciably slackened so that pulley 5I is pulled sharply upward and to the left as seen in Fig. 2 to the dotted line position shown at 65, or to an ever greater extent, depending upon the length and the elasticity of the belt lil. YIn this action, the belt lil is caused to be much more tightly seated in the. drive pulley 3S and driven pulley 43, and moreover, the angle produced between the right and left portions of the upper leg of the belt is appreciably sharpened, so that any reverse rotation of belt 43 such as that occasioned by upward bounce of the door sections is very strongly resisted. Moreover, if the door sections do rise even to the slightest extent, permitting pulley 43 to react in the counterclockwise,direction (Fig. 2) under the force of the countershaft spring, the upper leg of the belt is caused to move toV the left as seen in Fig. 2, and it carries the idler pulley to a. position of still further leftward deflection than that indicated at B5. Thus, the belt is very greatly tightened, and in view of the high ratio speed step-down gearing between the motor rotor proper and the motor drive pulley 39, the motor system and idler pulley arrangement as thus organized is fully effective to guard against counterclockwise rotation of the counterspring shaft. With this shaft fully blocked as in the abovedescribed condition, the doorv I3 is not positively locked downward by direct rigid connection of the pulley 43 or counterspring shaft, but being suspended by flexible cables, is now simply prevented froin being counterbalanced to any extent by the counterspring system. Hence, anyone attempting to open the garage door and enter therethrough would be compelled to Ylift the entire weight of the gara-ge door, a weight which generally is in excessof 200 pounds, and in the evnto large door units, may 'eikceed 4U() pounds. Thus, the idler "system as arranged 'conjunction with the above-described leg of the belt serves a purpose in strongly resisting intrusion as well as in suppressing rebound of the door and holding it closed upon arrival of the door lat its lowerinost position.

Upon driving the door to its lowermo'st position, the motor becomes stalled, and the motor circuit may be opened by a thermal lcut-off arrangement temporarily, or the alertness of `the operator may be relied upon for throwing the arm of switch to the oli position immediately after the door has been fully closed. Automatic door control apparatus for remote 'control from an automobile, as through a magnetic pulse transmitter system, may be `provided in place of the direct manual control switch i5 as illustrated in my copending application Serial No. 45,759, filed August 23, 194.8.

In 3 there is illustrated a preferred embodiment of the present invention wherein bilateral locking and belt tightening action is provided by tw'o elastically urged idler units--one working on each leg of the belt 'between the motor drive pulley 3e and the driven pulley on the counterspring shaft 2i The upper pulley 5l is journalled on the end of one arm 53', Aand the lower pulley 5l" is similarly journalledcn the end of the other arm 53". ri."l'iese arms 53 and 53 are pivoted about the motor drive pulley axis, and are urged toward each other by a tension spring il acting between them.

In this version oi the invention, the pulleys 5| and 5l" act on the broad flat outer surface of the V-belt, as illustrated in the detail crosssectional view of Fig. Ll, and accordingly these pulleys preferably are spool-like, with relatively long cylindrical sections flanged at the ends. They are accordingly made quite tolerant of the lateral position of the belt. Acting on the back of the belt, they increase the wrap-around on the pulleys. As these idler pulleys act at radius arms from the motor drive pulley se appreciably smaller than half the distance to the driven pulley d3 on the door counterspring shaft, they are able to increase the wrap-around on the motor drive pulley to well above 186, even if the diameter of this pulley is somewhat less than the diameter or the driven pulley.

Since this version of the invention is duolateral in its action, it is equally well suited for those installations where the door suspension cable 23 passes counterclockwise over the broadrim pulley or sheave 22, downward to the door as viewed in Fig. 1, and for those installations where it taires the opposite (clockwise) direction.

Furthermore, the arrangement of Fig. 3 not only provides locking action to suppress backlash or bounce of the door at the4 end of its descent and to resist Uninvited entry via the garage door, but moreover, it acts similarly to hold the door firm upon its arrival at the opposite extreme of its travel.

With the door suspension cable 23 passing countercloclwise downward in Fig. 3 just as in li i., the motor drive pulley 39 pulls the lower of the belt :il to provide descent oi the door. When the door reaches the lower limit of its travel, this leg of the belt is appreciably tightened, stretching it somewhat, and providing elongation of the upper leg of the belt, so that the upper pulley 5l is pulled sharply downward. The idler pulleys El' and lil then appear de :Elected downward from their running positions MAL.

assenso 'shown in Fig. tendency of the ldoor to rebound upward `acts to stretch the lower leg of the belt y'et further, so that the upper idler 5I is madeuto `deflect the upper leg of the belt even more. Under these conditions, the Vbelt is quite tightly `wedged in the motor drive pulley and in the driven pulley, insuring against any opening of 'the `door against the internal non-reversibleeaction gearing in the speed reduction system or the drive motor.

Upon driving the door to the ful-ly raised position, ,where it is blocked by the upper limit stop 'afiixed to the rails, the upper belt is tightened 4and the lower belt leg is slaclfzened., so that the lower idler pulley 5l" is drawn sharply upward, again insuring :against backlash in the systen. A

A `fea-ture of this embodiment of the `imlention is its adaptability `to door systems with the suspension cable extending downward from the door side 'of the countei'spring shaft sheave or with the suspension cable extending downward from the opposite side of the counterspring shaft sheave. As is immediately apparent, the sym metry of the arrangement of Fig. 3 makes it independent of the door drive direction, i. e., it operates equally well whether' the motor pulley 'operates clockwise to raise the door as shown, or in the `opposite direction.

Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In combination, a sectional garage door system including a pair of tracks extending upwardly and rearwardly, a door guided therein and including multiple hinge-connected sections, and a cross-shaft between said tracks and coue pled to said door, said cross-shaft having a V- pulley thereon; a motive unit for said door system including an electric motor having speed reduction gears and a low-speed output V-pulley aligned coplanarly with said cross-shaft V-pulley; an endless V-belt extending over said motor output V-pulley and said cross-shaft V-pulley and having appreciable slack therein; at least one idler pulley arm and one idler pulley thereon bearing against the leg of said belt wherein tension is exerted to raise said door, said idler pulley arm being pivotally mounted to enable said idler pulley to Contact said leg of said belt; means including said motive means for driving said door downward to the lower limit of its travel and stalling said motor, thereby increasing the length of the belt in said leg between said V-pulleys by virtue of the increased tension in the opposite leg of the V-belt; and means including said idler pulley arm and said idler pulley and elastic means coupled to said idler pulley arm for normally providing appreciable deilection in said contacted belt leg during movement of said door and for materially increasing the deection of said contacted leg of said belt and retaining it in the position of increased deflection when said door is forced to its closed position, thereby retaining the door closed with appreciable downward force exerted thereon after said motive means is deenergized.

2. In combination, an object movable in guide means between first and second opposite iixed 7 limitsn of travel, a r'st V-pulley coupled to said object, a reversible motive unit for said obk ject including an electric motor having speed reduction gears and a low-speed output V-pulley aligned with said first V-pulley, an endless V- belt extending over said first V-pulley and said motor output V-pulley and having appreciable slack therein for the' circuit over said V-pulleys, said reversible motive unit and said V-belt comprising means for driving said object at low speed between said first and second fixed limits of its travel, first and second idler pulley arms pivoted about the axis of said motor output V-pulley, said first arm having a first idler pulley in contact with the outer surface of the leg of said V- belt wherein tension is exerted to drive said object toward said first fixed limit and said second arm having a second idler pulley in contact rwith the outer surface of the leg of said V-belt wherein tension is exerted to drive said object toward said second fixed limit of its travel, a tension coupling between said first and second arms tending to pull each of said idler pulleys toward the other and to provide deflections of the respective legs of the belt, means including said reversible motive means for driving said object forcibly against said rst limit of its travel and stalling said mo- Jtor by the increased torque load thereon whereby said first idler pulley is forced outward by the increased tension in the belt leg in contact therewith, the second idler pulley and second arm being moved to a position of increased deflection by the increased slack in the leg of the belt in contact therewith and by the pull thereon communicated by said tension coupling as said rst pulley is forced outward, thereby retaining the movable object forced against said first fixed limit by the tension in said belt leg contacted by said first idler pulley after deenergization of said motor.

3. The combination defined in claim 2, wherein said object comprises a sectional garage door guided in side rails having vertical sections and slightly inclined sections, and said first pulley comprising a cross-shaft pulley on a shaft coupled to both sides of said door by drum-wound suspension cables.

i GEORGE F. RICHARDS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 439,790 Pollock Nov. 4, 1890 864,846 Jenney Sept. 3, 1907 976,115 Bard Nov. l5, 1910 1,222,090 Findley Apr. 10, 1917 1,897,391 Kelley Feb. 14, 1933 2,099,191 Blodgett Nov. 16, 1937 2,378,262 Vallen June 12, 1945 

